<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
    .box {
        display: flex;
        width: 100%;
        height: 80px;
        margin: 2px 0;
        background-color: bisque;
    }
    .col {
        flex: 1;
        background-color: aqua;
    }
    .col:nth-child(even) {
        background-color: aquamarine
    }
    </style>
</head>
<body>
    <div class="box">
        <div class="col"></div>
    </div>

    <div class="box">
        <div class="col"></div>
        <div class="col"></div>
        <div class="col"></div>
    </div>

    <div class="box">
        <div class="col"></div>
    </div>
</body>
</html>